Composite printing plate with a magnesium alloy bonded to an aluminum layer



Oct. 28, 1969 J, uss 3,475,140 COMPOSITE PRINTING PLATE WITH A MAGNESIUM ALLOY BONDED TO AN ALUMINUM LAYER Filed Jan. 5, 1966 INVENTOR, ROBERT J. RUSSELL United States Patent C US. Cl. 29183.5 4 Claims ABSTRACT OF THE DISCLOSURE A printing plate is shown to comprise a first layer of photoengravers magnesium and a second layer of aluminum, the first and second layers being metallurgically bonded together.

This invention relates to composite materials and articles made therefrom. More particularly, this invention relates to a composite material and a printing plate formed from a composite material including a layer of easily etchable material bonded to a layer of material having good tensile strength and flexibility.

It is an object of this invention to provide a composite material and an improved printing plate made therefrom which includes a surface which is easily etchable, and which provides a high quality printing surface, and yet which is strong enough to resist creeping, tearing or cracking and yet is flexible enough to permit bending and clamping of the end of the plate in a wrap-around or other form.

Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the element and combinations of elements, features of construction and arrangements of parts, all of which will be exemplified in the structure hereinafter described and the scope of the application of which will be indicated in the appended claims.

In the accompanying drawings in which one of various possible embodiments of the invention is illustrated:

FIG. 1 is a perspective view of a sheet of composite material according to this invention; and

FIG. 2 is an end view of a printing roller including a wrap-around printing plate formed of the composite material according to this invention.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Dimensions of certain of the parts as shown in the accompanying drawings have been modified for the purposes of clarity of illustration.

The composite material and printing plate contemplated by this invention is particularly adapted for use in the letter press process of printing. It is also suitable for use in offset printing.

In the letter press process of printing, it is desirable to provide a printing plate capable of being wrapped around the outside of a printing roll and capable of be ing clamped at its ends. To accomplish this, it is required that the printing plate be a thin, light material, that it be readily etchable, that it give a high quality printing surface and that it have high tensile strength and long wear life on a printing press and that it resist tearing, cracking or creeping.

Various kinds of magnesium alloys, know as photoengravers magnesium, have desirable etching characteristics in that the top or printing surface of the magnesium is not undercut by etching but rather tapers away from the top surafce to provide strength in the print plate and retain printing images. In addition, photoengravers magnesium etches to a depth that many other materials do not etch to. However, photoengravers magnesium cannot be used in a wrap-around type of printing in other than short runs since it is brittle and weak and tends to tear or crack. In addition, magnesium cannot be bent on very small radii as is necessary in wrap-around printing operations. Efiorts have been made to solve these problems by using various types of plastics. However, these materials are highly expensive and further do not provide a high quality printing surface that photoengravers magnesium provides. Further, the plastic does not achieve the high degree of fidelity in image that the magnesium does. And most important, plastics do not have the wear lift that photoengravers magnesium possesses, and further, cannot be chrome plated for printing applications, a feature which as is well known advantageously improves wear life. Applicant has provided a solution to these problems in this invention.

Turning now to the drawings, particularly FIG. 1, a composite material, generally indicated by reference numeral 10, is formed of a first layer 14 of photoengravers magnesium alloy and a second layer 12 of aluminum or aluminum alloy. Layers 12 and 14 are metallurgically bonded to each other at the molecular level by any suitable bonding method. The magnesium comprises approximately 60% of the thickness of composite plate 10 while the aluminum is approximately 40% of the thickness.

While there are several magnesium alloys suitable for photoengraving which provide the etching characteristics desirable for printing, preferred embodiments of applicants material are PE alloy, AZ61A alloy and other photoengraving alloys. PE alloy is composed of by weight between 2.5% and 4.0% aluminum; a max. of 0.08% manganese; between 0.7% and 1.6% zinc; a max. of 0.5% silicon; a max of 0.05% copper; a max of 0.005% nickel; a max of 0.005% iron and a max. of 0.04% cadimium; a max. of 0.030% of other impurities and the remainder magnesium. AZ16A alloy is composed of by weight between 5.8% and 7.2% aluminum; a min. of 0.15% maganese; 0.4% to 1.5% Zinc; a max. of 0.05% of silicon; a max. 0.05% copper; a max. of 0.005% of nickel; a max. of 0.005% of iron; a max. of 0.3% of other impurities and the remainder magnesium. This combination provides the optimum alloy for etching characteristics and printing quality and in addition the best alloy for processing that is, bonding to the aluminum layer. The .most important additives to the alloy serve to affect the grain structure of the magnesium and to make it adaptable to the etching process and hence provide the finer printing surface charactistics.

The aluminum 14 may be pure aluminum which is selected for strength and ductility or any one of a number of aluminum alloys may be employed so long as they provide the strength needed to withstand the bending and tension of a wrap-around printing plate and resist tearing and cracking as well as creeping.

In one embodiment of applicants material, the aluminum used was aluminum alloy No. 3003. This alloy includes a composition of between .1 and .15 by weight of manganese, a max. of .6% by weight of silicon, a max. of .7% by weight of iron, a max. of .2% by Weight of copper, a max. of .l% by weight of zinc, a max. of .15 by weight of other metals, and the balance aluminum. This particular alloy provides an excellent combination of strength and ductility. In another embodiment, aluminum alloy No. 1100 was used. This alloy includes a minimum of 99.0% aluminum and is known as commercially pure aluminum.

There is shown in FIG. 2, a portion of a printing roll employing applicants wrap around printing plate. On the periphery of roll 22 is located a wrap-around printing plate generally indicated by reference numeral 20. Plate 20 is plate wrapped around roll 22 and etched by any one of a number of known etching processes to provide etched portions 30 which form the desired printing surface 32 on the exterior of plate 22. .It will be understood that after the printing surface 32 has been etched and cleaned, the surface 32 may be chrome plated to improve the wear life of surface 32.

It will be further understood that etched portions 30 may have more or less regular walls and may or may not extend through layer 14 to layer 12 depending on the etch process used and the result desired.

As also seen in FIG. 2, roller 22 includes an open cavity or recess 24 into which ends 28 of plate extend. Included within recess 24 are gripping or tensioning means 26 which may be of any well known type which can grasp the ends 28 of plate 20 and tension and retain these ends in the recess 24 to hold the plate seen in FIG. 2, the magnesium layer 14 is preferably etched away in its entirety from the ends 28 of plate 20. This keeps the magnesium from cracking from the surface under the strain of being tensioned and under the strain of the bend which ends 28 undergo. The flexible and strong aluminum layer withstands the bend of end 28.

It can thus be seen that the objects of the invention are achieved and a composite material suitable for a wraparound printing plate has been developed which provides both a high quality printing surface and excellent etching characteristics and which is also strong and ductile so that the printing plate does not creep towards one end under the strain of continued printing and which does not crack or fracture at the bend point 28 and which is also capable of extended use in printing without wear.

In a co-pending application, Ser. No. 420,895, filed Dec. 24, 1964 in the names of Robert J. Russell and Francis T. Corcoran and assigned to the assignee of the instant invention, the use of a layer 14 formed of photoengravers zinc was disclosed. The instant invention constitutes an improvement in that the etching process for the photoengravers magnesium is substantially easier and cheaper in that the etch bath is more stable and does not deteriorate as quickly as the etch bath required for zinc. Further, it has been discovered that a phenomenon known as pimpling sometimes occurs in the etched portion 30 of layer 14. This pimpling consists of the formation of an etched portion in those portions 30 which should be etched. This deleteriously affects the quality of the printing surface. It has been discovered that the occurrence of this phenomenon is substantially reduced when layer 14 is formed of photoengravers magnesium. Finally, there is a substantially economic ad vantage which results from the use of magnesium in that the material is much lighter and is easier to handle and transport.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results are obtained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense,

4 and it is also intended that the appended claims shall cover all such equivalent variations as come within the true spirit and scope of the invention.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of elements illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

I claim:

1. A printing plate formed of a composite material comprising a first layer of magnesium alloy consisting essentially of, by weight, between 2.5% and 4.0% of aluminum; a max. of 0.08% manganese; between 0.7% and 1.6% zinc; a max. of 0.05% silicon; a max. of 0.05 copper; a max. of 0.005% nickel; a max. of 0.005% iron; a max. of 0.04% cadmium; a max. of 0.030% of other impurities and the remainder magnesium; and a second layer of aluminum alloy consisting essentially of from .1% to .15 by weight of manganese; a max. of .6% by weight of silicon; a max. of .7% by weight of iron; a max. of .2% by weight of copper; a max. of .1% by weight of zinc; a max. of .15% by weight of other elements and the balance aluminum; the first layer being metallurgically bonded to the second layer.

2. The printing plate set forth in claim 1 wherein said magnesium layer comprises 60% of the thickness of the composite material.

3. A printing plate formed of a composite material comprising a first layer of magnesium alloy consisting essentialy of, by weight, between 5.8% and 7.2% aluminum; a min. of 0.15% manganese; 0.4% to 1.5% zinc, a max. of 0.05 of silicon, a max. of 0.05% of copper, a max. of 0.005% of nickel, a max. of 0.005% iron, a max. of 0.3% of other impurities and the remainder magnesium; and a second layer of aluminum alloy consisting essentially of from .1% to .15% by weight of manganese, a max. of .6% by weight of silicon, a max. of .7 by weight of iron, a max. of .2% by weight of copper, a max. of .1% by weight of zinc, a max. of .15 by weight of other elements and the balance aluminum; the first layer being metallurgically bonded to the second layer.

4. A printing plate as set forth in claim 3 wherein said magnesium layer comprises 60% of the thickness of said composite material.

References Cited UNITED STATES PATENTS 2,366,185 1/1945 Diehl 29-1975 XR 2,704,512 12/1951 Alexander 101401.1 3,179,504- 4/ 1965 Bothwell 29197.5

OTHER REFERENCES Publication of application 119,753 (filed Oct. 1949), published Jan. 23, 1951.

Page 1021, American Society of Metals Handbook, 1948 edition, by American Society for Metals.

HYLAND BIZOT, Primary Examiner US. Cl. X.R. 29-1975; 10l458 

